Aquatic Sciences Meeting, Albuquerque 2001

SS02 Photochemical Reactions In Surface Waters: A Major Issue in the 21st Century? (Environmental Connections)

Date: Thursday, February 15, 2001, Time: 3:45:00 PM

Location: San Miguel

Kieber, R, J, UNC-Wilmington, Wilmington, USA, Kieberr@uncwil.edu

Willey, J, D, UNC-Wilmington, Wilmington, USA, Willeyj@uncwil.edu

Cooper, W, J, UNC-Wilmington, Wilmington, USA, Cooperw@uncwil.edu

TEMPORAL VARIABILITY OF IRON SPECIATION AND HYDROGEN PEROXIDE CONCENTRATIONS AT BATS: ATMOSPHERIC INFLUENCES ON SEAWATER CONCENTRATIONS

Temporal and seasonal variations in iron speciation and hydrogen peroxide concentrations were investigated during a summer and winter cruise aboard the RV “Endeavor” at the Bermuda Atlantic Time Series Station (BATS). Rainwater iron and hydrogen peroxide concentrations revealed both diel and seasonal variability with maximum values obtained in the summer several hours after sunset. Rainwater was the dominant source of both iron and hydrogen peroxide to surface seawater. Experiments utilizing authentic rainwater collected at BATS demonstrated atmospherically deposited Fe(II)(aq) is stabilized against oxidation for more than four hours in surface seawater. Depth profiles taken before and after rain events indicated that during periods of high rainfall activity, wet deposition is the most important source of oceanic hydrogen peroxide while in situ photochemical processes become relatively more important under periods of low rainfall. A conceptual model emphasizing the interplay between iron speciation, hydrogen peroxide and light intensity and the importance of these photochemical processes on the lifetime and stability of atmospherically deposited Fe and hydrogen peroxide in seawater is also presented.

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Aquatic Sciences Meeting, Albuquerque 2001

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